Mehmet Gokhan Caglayan

Silver Nanoparticle Based Analysis of Aminoglycosides

ABSTRACT Colorimetric silver nanoparticle sensor was developed for determination of aminoglycosides in milk. Silver nanoparticles were synthesized by using sodium borohydride as reducing agent and sodium dodecyl sulfate as stabilizer. Yellow color of silver turned into orange and red in proportion to the concentrations of analytes. Quantitative analyses were performed by using decrease in absorbance of silver nanoparticles at 394 nm. Linear ranges were 20–60 ng mL−1, 23–60 ng mL−1, and 60–100 ng mL−1 for gentamicin, tobramycin, and amikacin, respectively. The method was optimized in terms of pH, ionic strength, and time. This simple and validated method was applied to milk samples and pharmaceutical preparations.

Gold nanoparticle-lignan complexes inhibited MCF-7 cell proliferation in vitro: a novel conjugation for cancer therapy.

Nanoparticles, including gold nanoparticles (AuNP), have been used in imaging in cancer treatment and as therapeutic agents and drug delivery vehicles. Particularly lignans, also called phytoestrogens, have strong effects on the treatment of carcinomas due to their antiestrogenic, antiangiogenic and proapoptotic mechanism. The aim of this study is to investigate the antiproliferative effects of three lignans-AuNP conjugates, pinoresinol (PINO), lariciresinol (LARI) and secoisolariciresinol (SECO), on the MCF-7 cell lines. For this purpose, first, thiolated β-cyclodextrin (β-CD) was synthesized to achieve a surface modification of AuNP, and then the β-CD modified AuNP was characterized using the transmission electron microscopy (TEM), UV-Visible and Nuclear Magnetic Resonance (NMR) spectroscopy. Then, the selected lignans were conjugated to the β-CD-modified AuNP, and the antiproliferative effect of these conjugates was monitored. The results suggest that when compared to their non-conjugated forms, the AuNP-bound lignan conjugates prevented the proliferation of the MCF-7 cells significantly. Therefore, these AuNP-conjugated derivatives can be new candidate agents for breast cancer therapy.

STABILITY-INDICATING MICELLAR ELEKTROKINETIC CHROMATOGRAPHY METHOD FOR DETERMINATION OF FINASTERIDE IN PHARMACEUTICAL PREPARATIONS

A stability-indicating micellar electrokinetic chromatography method has been developed and validated for determination of finasteride. Analysis was performed by using 50 cm × 100 µm i.d. (effective length 42.8 cm) fused silica capillary and background electrolyte of 50 mM NaH2PO4 (pH 3) buffer containing 10 mM sodium dodecyl sulfate as surfactant. Applied potential was selected as −15 kV at 25°C and the detection was at 210 nm. The calibration curve was linear in the range of 5–50 µg · mL−1. Effects of pH, capillary temperature, applied voltage, and buffer concentration were investigated. Degradation studies were carried out under acidic (1.0 M HCl), basic (1.0 M NaOH), oxidative (%10 H2O2), thermal (60°C), and UV-light (254 nm) conditions and it was found that finasteride was degraded under acidic, basic, and oxidative stress conditions. The method was successfully applied to the determination of finasteride in tablet formulations.

Colchicine levels in chronic kidney diseases and kidney transplant recipients using tacrolimus.

Tacrolimus is a CYP3A4 inhibitor and can alter colchicine metabolism. In this study, we aimed to evaluate plasma colchicine levels in different stages of kidney disease as well as in kidney transplant (KTx) recipients using tacrolimus.

Optimisation and validation of liquid chromatographic and partial least-squares-1 methods for simultaneous determination of enalapril maleate and nitrendipine in pharmaceutical preparations

Simultaneous determination of enalapril maleate (ENA) and nitrendipine (NIT) in pharmaceutical preparations was performed using liquid chromatography (LC) and the partial least-squares-1 (PLS-1) method. In LC, the separation was achieved on a C8 column and the optimum mobile phase for good separation in a gradient elution programme was found to be acetonitrile-water (φr = 81: 19) and optimum flow-rate, temperature, injection volume, and detection wavelength were set at 1.0 mL min−1, 25°C, 10 μL, and 210 nm, respectively. Dienogest was selected as an internal standard. In the spectrophotometry, a PLS-1 chemometric method was used. The absorbance data matrix related to the concentration data matrix was established by measurement of absorbances in their zero order spectra with an increment of Δλ = 1 nm in the 220–290 nm range for ENA and with Δλ = 1 nm in the 230–290 nm range for NIT in the PLS-1 method. Following this step, calibration was established by using this data matrix to predict the unknown concentrations of ENA and NIT in their binary mixture. These optimised methods were validated and successfully applied to a pharmaceutical preparation in tablet form and the results were subjected to comparison.

Paper based lateral flow immunoassay for the enumeration of Escherichia coli in urine

In this experimental study, we developed lateral flow immunoassay strips for the detection of Escherichia coli. For labelling, gold nanoparticles were prepared and modified with a Raman label. As a result of this, not only colorimetric responses but also Raman responses were obtained from the same strips. The color and Raman intensities were employed for the quantitative determination of Escherichia coli. The employment of two different detection methods strengthens the quantitative determination of Escherichia coli by lateral flow immunoassay, which is mostly used for qualitative detection or sometimes the semi-quantitative determination of samples. After careful optimization and validation steps, the developed strips allowed the highly sensitive determination of Escherichia coli in water and urine samples.

Optical Sensing of Mercury Using Fluorescent Silver and Gold Nanoclusters

In this study, gold and silver nanoclusters were employed for optical sensing of mercury. Nanoclusters used in this research had different chemical properties and showed different interactions with mercury producing specific optical responses including UV-Vis absorbance and f luorescence. These responses were quantitatively studied in the solution phase. The sensitive methods developed in this study were tested using mercury standards and accurate and precise results were obtained. Optical responses could also be monitored by naked eye. Finally, portable and simple glass fiber pads were developed for mercury sensing.

The Effects of 1,3,5-trisubstituted Indole Derivatives on Cell Growth, Apoptosis and MMP-2/9 mRNA Expression of MCF-7 Human Breast Cancer Cells

BACKGROUND Matrix metalloproteinases are known as extracellular matrix degrading enzymes and have important role on tumor progression. OBJECTIVE This study reports the effects of 1,3,5-trisubstituted indole derivatives on cytotoxicity, apoptosis and MMP- 2/MMP-9 mRNA expression of MCF-7 human breast carcinoma cells. METHOD The cytotoxic effects of the compounds on MCF-7 cells were performed by MTT test, and cell proliferation was determined via BrdU incorporation. The apoptotic effects were observed by cell death detection elisa. The effects of the compounds on MMP-2/-9 enzyme activity and mRNA expression were also performed. RESULTS The compounds inhibited the proliferation of MCF-7 breast carcinoma cells significantly in a dose dependent manner. All compounds were able to induce DNA fragmentation, especially compound 1. The IC50 values of compound 2 and 4 for MMP-2 were 0.42 μM and 1.88 μM, respectively. MMP-2 mRNA expression results were correlated with the inhibition of enzyme activity, such compound 4 inhibited MMP-2 mRNA expression at all treated concentrations. Docking simulation has also been performed to analyze the binding mode of compounds and the results showed that compound 2, the most active compound, formed a hydrogen bond with Glu202 for binding to the MMP-2 active site. In addition, the hydrophobic parts of compound 2 are in contact with nonpolar surface areas of MMP-2, such as His201, His211, Tyr223 and Tyr193. CONCLUSION According to the molecular docking results along with the biological assay data, it is suggested that compound 2 might be used for further design and development of MMP-2 inhibitors.

A metal-enhanced fluorescence study of primary amines: determination of aminoglycosides with europium and gold nanoparticles

This paper describes a lipoic acid capped europium nanoparticle-based assay for the fluorimetric detection of primary amines. The assay is based on fluorescence quenching resulting from complex formation between amines and lipoic acid on the surface of europium nanoparticles. For the application of the assay, the aminoglycosides were determined in pharmaceuticals and milk. The determination of the aminoglycosides were conducted via fluorescence quenching at 315 nm (λex = 280 nm) at a pH of 5. The metal enhanced fluorescence method with gold nanoparticles was used, in order to enhance the fluorescence of europium nanoparticles. In this manner, the detection limits of aminoglycosides were lowered. The Stern–Volmer constants and the ground-state UV spectra of interaction proved the static quenching that stemmed from the reaction between amines and lipoic acid. Three members of aminoglycosides; amikacin, gentamicin and tobramycin were quantified in the range of 0.75–27.5 μg mL−1, 0.40–26 μg mL−1 and 0.20–25 μg mL−1, respectively.

Using derivative and ratio spectra derivative: spectrophotometries as new data preprocessing method in partial least squares technique for resolving overlapped spectra of montelukast sodium, desloratadine, and levocetirizine dihydrochloride

Abstract Chemometric techniques are widely used for resolving overlapped spectra in different analysis type including simultaneous determination of active ingredients in pharmaceutical preparation. Processed data are used in some instances alternative to the raw data. Standardization, normalization, and mean centering are preferred data preprocessing methods in multivariate analysis techniques. In this study, derivative and ratio spectra derivative spectrophotometric methods are used in preprocessing for spectrophotometric data as an alternative to the other procedure in partial least squares technique (PLS-1) for resolving overlapped spectra of ternary mixtures of montelukast sodium, desloratadine, and levocetirizine dihydrochloride. Simultaneous determination and quantitation of these active ingredients from their bulk solutions and pharmaceutical preparations was achieved successfully by this developed and optimized partial least squares method. These results indicate that derivative and ratio spectra derivative spectrophotometric methods will be used as a new data preprocessing method in chemometric techniques from now on.